Separately, Democratic U.S. Sen. Kirsten Gillibrand scored a big victory in the state over Republican conservative activist Wendy Long.
Obama defeated the former Massachusetts governor, 62 percent to 36 percent, with virtually all votes counted, winning New York's 29 electoral votes.
Gillibrand beat Long, 72 percent to 27 percent, with almost all results tallied.
Independent candidate Colia Clark picked up 0.6 percent, Libertarian Party nominee Chris Edes tallied 0.5 percent and independent John Mangelli picked up 0.3 percent.
Gillibrand's win elected her to her first full, six-year term. She was named by New York's governor in 2009 to fill the Senate seat of Hillary Clinton after President-elect Obama named her as secretary of state.
Gillibrand was required to run in a special election in 2010, which she won with 63 percent of the vote.
Long is a New York City lawyer involved with a conservative advocacy group who was making her first run for public office.
In key House races:
-- Republican Rep. Michael Grimm kept his 11th Congressional District seat, representing Staten Island and part of Brooklyn, defeating Democratic challenger Mark Murphy.
-- Republican Rep. Chris Gibson won a second House term, defeating Democratic challenger Julian Schreibman, but in the new 19th Congressional District covering the Hudson Valley and Catskills north of New York City. Gibson currently represents the 20th district, which is being altered after the 2010 U.S. Census.
-- Democratic candidate Dan Maffei upset incumbent GOP Rep. Ann Marie Buerkle in the new 24th Congressional District. Buerkle had upset Maffei two years ago in the 25th Congressional District that the new district replaces.
-- Republican former Erie County Executive Chris Collins unseated Rep. Kathy Hochul in a tight race for the 27th Congressional District, representing Buffalo, some suburbs and Jamestown. Hochul balked at conceding the race.